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WD Red NAS 4TB 3.5” 5400RPM SATA Internal Hard Drive (WD40EFAX)

Model Number: WD-40EFAX-US
Web Code: 14896380

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For up to 24 bay medium to large-scale NAS environments, the WD Red Pro drive is engineered to handle increased business workloads and carries a 5-year limited warranty.

Available online only

Delivery times vary by location. Most Marketplace items leave sellers' locations within 2 business days. Allow additional time for shipping.


For up to 24 bay medium to large-scale NAS environments, the WD Red Pro drive is engineered to handle increased business workloads and carries a 5-year limited warranty.

• Add value to your business by enabling your employees to quickly and reliably sync their files and back up folders or share work with clients.

• Seamless integration, robust data protection and optimal performance for larger NAS systems that demand more.

• WD Red Pro hard drives also have NASware technology and are purpose-built to balance performance and reliability in larger NAS and RAID environments.

• A multi-axis shock sensor automatically detects subtle shock events that may occur in larger NAS environments and when combined with dynamic fly height technology, helps to adjust each read-write function to compensate for increased vibrations and protect data.

• Desktop drives aren't purpose-built for NAS. But WD Red Pro drives with NASware 3.0 are. Our exclusive technology takes the guesswork out of selecting a drive. We can help you find the perfect storage for your NAS system.


Storage Drive Type
Desktop Hard Drive
Internal or External
Form Factor
3.5 in
PC/Mac Compatibility


4 GB
Rotations Per Minute (RPM)
5400 rpm




Seller's Warranty - Parts
3 Years
Seller's Warranty - Labour
3 Years

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Rating Breakdown












  • Quick replacement of one-half MyCloud Mirror
    Verified BuyerReviewed by Himself - June 11, 2021

    My MyCloud runs continuously for years. I replaced one drive last year with a new WD40EFAX. It was a simple procedure and the MyCloud quickly mirrored the good drive onto the new one. Has been running about six months with nary a hiccup.

    Review originally posted on Western Digital

  • Good Hard Drives For The NAS
    Verified BuyerReviewed by Roy L - June 10, 2021

    I got them for my NAS. All the drives were shipped at once and arrived quickly and in good condition. All of them installed perfectly and have been working great, 24/7 for the past few months without a single issue.

    Review originally posted on Western Digital

  • Great buy and easy to set up.
    Verified BuyerReviewed by Reid C - June 10, 2021

    Excellent hardware and easy to install. Loaded with features for local cloud sharing.

    Review originally posted on Western Digital

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Shipping Cost

Seller offers free standard shipping on all orders.

**In the event that product is unavailable, you will be refunded within 48 business hours.

Large Item Scheduled Delivery (items heavier than 150lbs)

Delivery Method

Product will be delivered outside your home for all shipping areas.
Recycling of your old item(s) is not included with delivery.
Assembly of the delivered product is not included.

Returns can be made within 30 days of receiving your order.

myNovaWay Restocking Fees / Return Eligibility
Category Return Period Un-opened Opened/Unused Opened/Used
Headphones and Earphones (all types), Baby, Juvenile & Maternity Products, Beauty, Grooming & Personal Products, Personal Care, Fitness Equipment & Accessories, Virtual Reality Headsets (Oculus Rift, PlayStation VR, etc.) 30 Days 0% Not Returnable Not Returnable
Furniture & Décor, Home Office Furniture, Musical Instrument Consumables (Guitar Strings, Microphones, etc.) 30 Days 0% 10% Not Returnable
All other products 30 Days 0% 10% 20%

Must be unassembled and still in the original packaging. All returned products must include original packaging.

Return shipping costs will be paid by the seller for all cases where the product is defective, damaged or incorrect. For other cases (e.g. you changed your mind), you will be responsible for this cost.

To request a return

Please contact the seller directly from your Order details page, and provide the following information:

  • Web ID (8-digit number) & product description
  • Number of items to be returned
  • Date you received your product
  • Condition of product
  • Condition of packaging
  • Reason for return

All refunds will be processed within 4 Business Days.